Serena Williams has defeated Li Na, 7-5, 6-1 to win a record seventh title at the Miami Masters after a slow start against the second seed from China.

Williams dropped serve in a six-minute opening game and trailed 2-5 in the first set before lifting her level to secure the trophy victory in two hours, with Li limited to three aces and managing 29 winners and the same number of unforced errors.

She broke Li on five of 17 opportunities.

Williams, who first played the tournament at age 16 and won the first of her titles a dozen years ago, said she had to recover in a tough opening set lasting 73 minutes.

“That was an important victory, Li started out so well, I tried just to hang in and enjoy myself,” she said after the game on Saturday.

“When I trailed 5-2 I had nothing to lose, so I was able to relax and start to play.”

Williams has now beaten Australian Open champion Li in 11 of 12 matches following their previous meeting at the year-end championships last autumn.

Williams triumphed in her ninth Miami final, her most at any WTA event and holds a 7-2 record at her home event.

The 32-year-old American was playing as top seed in her 50th tournament and has now won titles in half of them.

She finished with a service winner out wide which Li could barely get a racquet on.

Williams joins Chris Evert, Steffi Graf and Martina Navratilova as winner of seven tournaments.